The microstructure of food can be engineered to enhance sodium release during mastication, which may be used as a strategy to reduce sodium content in foods. This study aimed to relate sodium release to microstructural properties of solid lipoproteic colloid (SLC) foods. The SLC gels with 1.5% (w/w) NaCl were prepared by homogenization of whey protein isolate and anhydrous milk fat, followed by heat-induced gelation. The gels varied in protein content (8% or 16%), fat content (0%, 11%, 22%, or 33%), and homogenization pressures (14 or 55 MPa). The maximum rate of sodium release during the initial gel compression increased with increasing gel porosity and pore size. This was due to more releasable serum in the gels with larger pore volume and larger pores. The maximum concentration of sodium at the end of sodium release increased with reduced size of the fat particles in the gels. The smaller fat particles were dispersed more uniformly and interrupted the protein network more, and facilitated the gel breakdown. The above findings suggested that, during the breakdown of the SLC gels, the major mechanisms of sodium release are via serum release followed by sodium diffusion, which are governed by the gel porosity and the particle size of fat, respectively. This study demonstrated the dependence of temporal sodium release properties on the microstructural properties of an SLC food system. The findings from this study could lay the foundation for further investigation of the dependence of saltiness perception on SLC microstructure, which can provide insight for sodium reduction in SLC products.

Enhancing sodium release from the food matrix, thus increasing saltiness perception, is a promising strategy to reduce the amount of salt needed in foods. However, the complex nature of the effect of the food matrix on saltiness perception makes it difficult to control saltiness perception when designing food products. The aim of this review is to provide an overview of the food matrix effects on saltiness perception of sodium chloride. The effects are discussed in the order of 3 stages in saltiness perception: release of sodium from food matrix into oral cavity (1st stage), delivery of sodium within oral cavity (2nd stage), and detection of sodium by the taste receptor cells (TRCs) (3rd stage). In the 1st stage, the food matrix affects the initial availability of sodium to be released, and also affects the spontaneous and facilitated migration of sodium from the matrix into the oral cavity. In the 2nd stage, the food matrix affects the availability of sodium and the mixing efficiency of sodium with saliva. The relationship between food matrix and oral processing of food that may affect the sodium release (1st stage) and the delivery (2nd stage) is also discussed. In the 3rd stage, the food matrix affects the physical availability of sodium for the TRCs, the physiological activity of TRCs, and the central activities involved in the perception process. Based on the understanding of complex nature of the matrix effects on saltiness perception discussed in this review, the properties of food matrix may be controlled effectively to enhance saltiness perception and achieve sodium reduction.

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Sodium reduction in protein/lipid-based products such as cheese is becoming increasingly important to the food industry. Understanding the structure critical to sodium release is one of the keys to effectively controlling the sensory quality of the product while lowering the sodium content. In this study, ultra-small-angle X-ray scattering (USAXS), novel to food research, was used to characterize the structure of solid lipoproteic colloid (SLC) gels as a model food. The SLC gels were made via heat-induced gelation of emulsions of whey protein isolate and anhydrous milk fat. The gels varied in the contents of protein, fat, and NaCl and homogenization pressures. The gyration radii of the protein aggregates (r g,p) and the fat globules (r g,f) of the samples before and after the gelation were obtained via fitting the USAXS profiles to inspect the structure formation of the SLC gels. The effects of formulation and processing on the gel r g,p and the gel r g,f were analyzed. In addition, the gel r g,f and the hydrodynamic radius of the droplets (r h,e) in the emulsions were correlated with sodium release. The correlation suggested that gel r g,f is a better indicator of sodium release than the emulsion r h,e. The findings from this study indicated that USAXS is feasible for the structural investigation of protein/lipid-based foods.

Countries around the world have been implementing public health interventions to provide vitamins and minerals. There is a concern that the cumulative micronutrient contribution of coexisting programs, when targeting the same population, may exceed their safe levels of intake, thus potentially challenging the primum non nocere principle. We assessed the regulatory framework of such interventions and determined qualitatively whether there were provisions in the regulations that called for coordination among programs to ensure their innocuousness. Country cases from various WHO regions were selected for the study: (1) the Americas: Chile, Costa Rica, and Guatemala; (2) Africa: Malawi, Uganda, and Zambia; (3) South Asia: Bangladesh; and (4) the Western Pacific Region: China and the Philippines. We did not identify any provisions in the existing regulations requiring coordination mechanisms among interventions. However, in some countries, governments have established national micronutrient fortification commissions or alliances aimed to foster interprogram coordination. Their focus, however, has been mostly on the efficacy of the programs and less on their safety. A regulatory framework for coexisting micronutrient interventions should be comprehensive, accounting for all micronutrient sources and including regulatory provisions for coordination among programs.